Backfire release for internal combustion engines



BACKFIRE RELEASE FOR INTERNAL COMBUSTION ENGINES J w E Am w 0 4L A 7 M k 1 w flaw m W H 1 w a 9 5 L "I J, w [r k a M V V M 1 i m A FY W m n w n Aug. 2, 1938.

Patented Aug. 2, 1938 UNITED STATES PATENT. OFFICE BACKFIRE RELEASE FOR INTERNAL COM- BUSTION ENGINES Application October 31, 1931, Serial No. 572,258

15 Claims.

This invention relates to a back-lire release for internal combustion engines and more particularly a device for minimizing the effect of backward rotation of an internal combustion engine on the auxiliary mechanism thereof and especially on the starting mechanism therefor.

It is well known that the accidental actuation of the starting mechanism when an internal combustion engine is rotating backward causes heavy 1'0 stresses to be developed which may cause failure of the parts. When an automatic starting mechanism is employed for causing the engine to be cranked repeatedly until a successful start is secured, it therefore becomes important to prevent the operation thereof during backward rotation of the engine.

It is an object of this invention to provide novel means to prevent actuation of a starting mechanism during reverse rotation of the internal combustion engine.

Another object of the invention is to provide an automatic starting mechanism having novel means to maintain the starting mechanism inoperative while the engine is rotating backward.

for use in connection with automatic starting mechanism for rendering such starting mechanism inoperative during reverse rotation of the engine, but automatically restoring the starting mechanism to operative condition when the reverse rotation ceases.

Further objects and advantages will be apparent to those skilled in this art from the following description taken in connection with the accompanying drawing in which:

Fig. 1 is a semi-diagrammatic view of a preferred embodimentof the invention shown in connection. with an automatic starting mechanism of known type; and

Fig. 2 is an enlarged mid-sectional view of the back-fire releasing device.

Referring to the drawing, an electrical starting system for an internal combustion'engine (not shown) is illustrated comprising a battery i grounded at 2 and connected to a starting motor SM through a lead 3 and an automatic controlling device indicated generally at 4 and comprising a starting switch 5 adapted to be closed by energization of a solenoid 6. Solenoid 6 is embodied in a control circuit including the ignition switch 1 of the engine, lead 8, lead [contacts ii and ground connection l2. Contacts H are arranged to be opened by the action of alever it which is moved by a solenoid plunger i4 to bend back the spring strip i5 carrying one of the contacts A further object is to provide a novel device" ii when the engine starts. The plunger i4 is maintained in its lower position by means of a coil is energized from the generator G while the engine is in normal operation.

The device so far described and the operation thereof are known in the art, but it has been found that the generator coil i6 as usually constructed is not energized by the generator G sufilciently to retain the plunger l4 in its retracted position when the engine is rotating backward such as occasionally occurs for instance in the case of back-fire.

The present invention provides means to prevent the reactuation of the starting mechanism during back-fire conditions in spite of the deenergization of the generator coil l6, and the present embodiment employs for this purpose a .device for breaking the control circuit of the solenoid 6 during backward rotation of the en gine. As best shown in Fig. 2, this device comprises a casing il connected to the intake system of the engine as by means of an extension I8 threaded into the intake manifold of the engine, a portion of which is indicated at IS. A metallic diaphragm 2| is rigidly mounted in the casing H in a manner to form a closed chamber 22 in such casing, which chamber is in communication with the gases in the intake manifold through a passage 23 in the threaded extension i8. The diaphragm 2i is insulated from the casing as indicated at 24 and is connected as by means of a lead 25 to an insulated binding post 26 in the side of the casing. A contact 21 is carried by the diaphragm in position to normally engage a fixed contact 28 mounted on a bracket 29 connected to a second insulated binding post 3| in the side of the casing. The space 32 above the diaphragm is preferably vented to the atmosphere as indicated at 33, and a spring 34 is preferably provided for insuring the normal engagement of contacts 2'! and 28.

The back-fire releasing device is placed in the control circuit of solenoid 8, and, as shown in Fig. 1, is preferably inserted in the lead 8 of the control circuit,- the ends thereof being attached to the binding posts 26 and Si whereby the contacts 21 and 28 are placed in series in the controlling circuit, and opening of said contacts renders solenoid 6 inoperative.

In operation, and starting with the parts in the positions illustrated, closure of the ignition switch 1 causes energization' of the solenoid 6 to close the starting switch 5 and cause the engine, not illustrated, to be cranked. If the engine starts properly, the control plunger I4 is moved to open contacts ii and is held in its retracted position bythsgeneratorcoil lisslongastheengineis runllng. Howevenifthecngineshouldgiveone or two explosions suihcient to disconnect the starting gearing and thereafter should back-fire, the generator coil II is deenergized and the contacts aliowedtociose. 'Iheimmediateoperation of the starting mechanism is prevented, however, dnoe the backward rotation of the engine operataasapumptoforcegasbackinto the intake m thus creating a pressure therein which is increased by the back-firing explosions. This we in the intake system is transmitted through the passage 23 to the-diaphragm 2| cam the contact 21 to be moved away from contact II, thus breahng the control circuit for the solenoid I and preventing closing of the starting switch as long as the pressure in the intake manifold persists. when the backward rotation ceases, the pressure in the intake system is dupated and the diaphragm 2i, assisted if necemary by the spring 34, returns the contact 21 into magement with fixed contact 20, thus completing the control circuit and causing the creating operation to be repeated.

In adato provide sufiicient time delay to ensure the opening of contacts 21, It by the intake measure before effective closure of contacts II, the spring strip II is provided at its free end with a weight I. which, when released by the lever II, vibrates the spring strip for a suitable time beforecoming to rest and permitting effective closure of contacts Ii.

It will thus be seen that there is here provided a device which automatically prevents the actuation the starting mechanism while the engine is rota rearwardly, but which restores the parts to operative condition when the rearward rotation ceases. It will be understood that the invention is not restricted to the details of the anbodiment illustrated, since other embodiments utilising the principles of the invention will readily suggest themselves to those skilled in the art, and since various changes may be made in the arrangements and methods of cooperation,

of the parts without departing from the spirit of the invmtion as defined in the claims append hereto.

What is claimed is:-

I. In comilnation with an internal combustion engine having a fuel intake system and starting mechanism therefor, means actuated by positive pressure in the intake system of the engine greater than atmospheric pressure for preventing actuation of the starting mechanism.

2. In cmnbination an internal combustion engine having an intake system functioning at subatmoqwheric pressure during normal operation of the canine, starting mechanism therefor includlns a starting switch, m n y controllable means for actuating said starting switch, and mean responsive to positive pressure in said intake system for preventing the actuation of said 3. In cmnbination with an internal combustion engine having a fuel intake system, a starting mechanism therefor including a starting switch, means including a control circuit for actuating said starting switch, and means responsivetopositfvepressureinthe intake system of the engine above atmospheric pressure for preventing actuation of the control circuit to close the starting switch;

4. In emnbination with an internal combustionenginehavingafuelintakesystem,an

automatic starting mechanism therefor including manually controllable means for cranking said engine whenever forward rotation thereof ceases,andmeansactuatedbypositivepressurc intheintakesystemofthecngineaboveatmospheric pressure for preventing such cranking, said latter means-being arranged to cause cranking to take place automatically as soon as the positive pressure in the intake system of the engine is dimipated.

5. An automatic controller for internal combustion engine starters comprising with an internal combustion engine, a starting motor circuit, an electro-magnetic switch in said circuit for controlling energizing of the motor, a relay controlling the energizing of said electro-magnetic switch and including contacts, and means actuated by pressure above atmosphere in the intake manifold for maintaining said contacts separated.

8. An automatic controller for internal combustion engine starters comprising with an internal combustion engine, a starting motor circuit, an electro-magnetic switch in said circuit for controlling energizing of the motor, a relay controlling the energizing of said electro-magnetic switch and including contacts, and means actuated by pressure above atmosphere in the intake manifold for maintaining said contacts separated, said means including a flexible diaphragm.

7. An automatic controller for internal combustion engine starters comprising with an internal combustion engine, a starting motor circuit, an electro-magnetic switch in said circuit for controlling energizing of the motor, a relay controlling the energizing of said electro-magnetic switch and including contacts, and means actuated by pressure above atmosphere in the intake manifold for maintaining said contacts separated, said means including a movable member subjected to such pressure.

8. In an automatic controller for internal combustion engine starters, an ignition circuit. a starting motor circuit, and means comprising a pressure-operated device for maintaining said starting motor circuit open after ignition occurs when pressure above atmosphere exists in the engine manifold.

9. In an automatic controller for internal combustion engine starters, an ignition circuit, a starting motor circuit, and means for maintaining said starting motor, circuit open after ignition occurs when pressure above atmosphere exists in the engine manifold, comprising a pair of contacts and a pressure-operated device for opening said contacts.

10. In combination with an engine rotatable in opposite directions but operable in only one associated with said mechanism, said means be-' ing associated with the manifold to render said mechanism inoperative while reverse engine rotation is occurring, and operative thereafter.

12. In combination, an engine, a starter, and

and automatic starter operating an automaticstarteractuatingsystemopera-Il tive, upon stalling oi the engine, to actuate the starter, means associated with said system tending to render it inoperative during back-firing of the engine, and automatic means associated with said system tending to render it operative upon final stopping of the engine.

13. In an engine, the combination with an en gine starting system including a starter device having automatic energizing control means associated therewith efiective upon stopping of the engine, of fluid pressure means associated with said system automatically to render said control means inoperative when the engine back-fires and automatically to render said control means operative when the engine stops after back-firing.

14. In an automatic controller for internal combustion engine starters, a starting motor circuit, and means comprising a pressure-operated device for maintaining said starting motor circuit open when pressure above atmospheric exists in the engine intake manifold.

15. In an automatic control for internal combustion engine starters, a starting motor circuit, and means for maintaining said starting motor circuit open when pressure above atmospheric exists in the engine intake manifold comprising a pair of contacts, and a pressure-operated device for opening said contacts.

MALCOLM P. FERGUSON. 

